Container base



FIG. 1 is a top view of a container base embodying my new design;

FIG. 2 is a front side view thereof;

FIG. 3 is a right side view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a back side view thereof; and,

FIG. 6 is a bottom view thereof. 

The ornamental design for a container base, as shown. 